Telmisartan (INN) is an angiotensin II receptor antagonist developed for the treatment of hypertension and other medical indications as disclosed in EP 502 314 A (corresponding to U.S. Pat. No. 5,591,762). Telmisartan's chemical name is 4′-[2-n-propyl-4-methyl-6-(1-methylbenzimidazol-2-yl)benzimidazol-1-ylmethyl]biphenyl-2-carboxylic acid and has the following structure:

Telmisartan is generally manufactured and supplied in the free acid form. As disclosed in WO 00/43370 (corresponding to U.S. Pat. Nos. 6,358,986 and 6,410,742), each of which is hereby incorporated by reference, crystalline telmisartan exists in two polymorphic forms having different melting points. Under the influence of heat and humidity, the lower melting polymorph B transforms irreversibly into the higher melting polymorph A. Both forms are characterized by a very poor solubility in aqueous |systems| at the physiological pH range of the gastrointestinal tract of between pH 1 to 7.
Telmisartan is obtainable on the market under the trademark MICARDIS®. Starting from the free acid form, telmisartan as introduced to the market is manufactured using an expensive spray-drying process. Due to the poor solubility of the free acid form, preparation of alternative telmisartan formulation is difficult.